Osama bin Laden’s death is an occasion for celebration. President Obama should be commended for launching the operation, and the quiet professionals who carried out the dangerous mission deserve our thanks. Those who lost family and friends that Tuesday morning nearly ten years ago should draw some solace from the fact that the man who was ultimately responsible for killing so many innocents can no longer do so.

Bin Laden’s death will affect the course of the ongoing war on al Qaeda and its affiliates. Individuals matter a great deal in determining the course of history, a fact that applies to terrorist organizations as well as states. Who emerges as the leader of al Qaeda will be enormously consequential for the movement’s direction and appeal throughout the Muslim world. Just as he served as the glue that held various factions within al Qaeda together over the years, so too will his death affect all Qaeda going forward. To take but one example, Bin Laden’s longtime deputy, the Egyptian Ayman al Zawahiri, has repeatedly emphasized Egypt as the centerpiece of al Qaeda’s quest to re-establish a caliphate in the heart of the Islamic world. At the same time, al Qaeda has become more decentralized in recent years with the emergence of al Qaeda’s franchises: al Qaeda on the Arabian Peninsula, al Qaeda in the Islamic Maghreb (AQIM), and al Qaeda in the Land of Two Rivers (Iraq). These groups appear to operate with little guidance from Bin Laden or his close associates in Pakistan.

There will be a temptation among some quarters at home and abroad to declare, "Mission accomplished". Opponents of the war in Afghanistan will cite Bin Laden’s death as evidence strengthening the case for reducing U.S. forces in the region. Those who oppose a vigorous internationalist strategy will escalate their calls for the United States to adopt more of an "offshore" role. The Pakistanis will attempt to tout their cooperation with the United States in bringing bin Laden to justice while diverting American attention from such uncomfortable questions as how and why bin Laden was able to live for months or years under the noses of Pakistani military and intelligence officers. Other partners, whose enthusiasm for defeating al Qaeda has been limited, may be perfectly willing to declare victory and go home.

This temptation must be resisted, however. Protracted wars are not decided on the outcome of any individual episode. Rather, they turn on the progressive attrition of the adversary’s sources of power. Similarly, this conflict will not end in a single battle or campaign. Rather, al Qaeda and its extremist vision will be defeated through the patient accumulation of quiet successes. Victory will include discrediting extremist ideology, creating fissures between and among extremist groups, and reducing them to the level of a nuisance, groups that can be tracked and handled by local law enforcement groups.

An evil man can no do no more harm. However, an evil organization animated by a malignant ideology persists. Much work remains to be done.